Today broadcast video content is available in both a 4:3 ratio and 16:9 ratio formats. Typically, standard definition (“SD”) broadcast video is sent in 4:3 and high definition (“HD”) broadcast video is sent in 16:9. However, sometimes television broadcasters send HD video signals containing programs that were originally filmed in the 4:3 format (“Ratio Mismatch”). In this instance, the HD broadcaster must add vertical bars (“Pillar Bars”) to the left and right sides of the picture to fill the entire 16:9 HD display area. These Pillar Bars are typically black in color, but also may be gray, or some other color or graphic.
In the case of a Ratio Mismatch where 16:9 content is sent in a 4:3 video stream, horizontal Pillar Bars are added to the top and bottom of the picture to fill the entire 4:3 display area. Horizontal Pillar Bars are also commonly referred to as “Letterbox Bars”. As used herein the term “Pillar Bars” is used with reference to both vertical (left and right) bars and horizontal (top and bottom) bars.
To compensate for the above-described Ratio Mismatch, 16:9 HD televisions/displays and set top boxes typically have a manual “Zoom” function. The “Zoom” function is usually implemented via a button on an associated remote control to (i) stretch the image horizontally to remove the Pillar Bars thereby compromising the aspect ratio, or (ii) stretch the image both horizontally and vertically thereby filling the display and preserving aspect ratio, while sacrificing a portion of the top and bottom of the image. (The “Zoom” feature can also prevent uneven display degradation on plasma monitors.) This manual “Zoom” process is totally controlled by the end user and can be imprecise, inconsistent, and time consuming because the end user is required to press a button(s) on the remote control and step/cycle through Zoom states. Further, when the video content changes ratio (the Pillar Bars disappear or change size, for example), the end user will again have to re-adjust the Zoom, either “in” or “out” manually. In addition, if the video content changes ratio when the end user is performing their manual Zoom, the end user will become highly frustrated, as the end user attempts to Zoom to compensate for a ratio which has since passed. An end user's only other option is to select a static zoom setting, which may under or over Zoom depending on the Ratio Mismatched video content size.
Thus, what is needed is a method which provides a more consistent and efficient process for zooming “in” and “out” a video content stream to adjust for Ratio Mismatches and changes in the Pillar Bars.